Patients with SLE have increased numbers of B cells producing antibodies, including autoantibodies. T cells which regulate antibody production by B cells include helper cells, suppressor cells, and induces of each. Patients with SLE have a decrease in numbers and percentages of suppressor inducer cells both functionally and as measured by cells with the phenotype CD 4+, 2H4+. This abnormality is especially common in patients with active disease and in those with renal disease (especially with disease activity). Patient with SLE were found to produce antibodies reactive with recombinant hnRNP core protein A1. Such antibodies also were made by some patients with juvenile RA. Since this protein binds nucleic acids, it could induce anti-DNA (or vice versa) by internal image idiotypic mechanisms. We looked for, but could not find, evidence for an idiotypic induction of such antibodies: anti-DNA and anti-hnRNP core protein A1 antibodies bore no special temporal relationship with each other. Immunization of mice with recombinant hnRNP A1 protein led to large amounts of anti-hnRNP core protein suggesting that direct immunization might be the mechanism of induction in people.